In manufacturing processes of a semiconductor device, there is a process of forming a silicon-based insulating film such as a silicon oxide film (SiO2) and a silicon nitride film (Si3N4), that is, an insulating film that contains silicon as a predetermined element, on a substrate such as a silicon wafer. The silicon oxide film has excellent insulating properties, low dielectric properties or the like, and thus is widely used as an insulating film and an interlayer film. Furthermore, the silicon nitride film has excellent insulating properties, anticorrosion properties, dielectric properties, film stress control properties or the like, and thus is widely used as an insulating film, a mask film, an electric charge storage film, a stress control film or the like. Furthermore, a technique of adding carbon (C) to the insulting films is also known, and thereby etching tolerance of the insulating film can be improved.